Conventional ultrasound scanners have hardware configurations such as linear scanning with beamforming for transmit and receive operations that limit the types of imaging algorithms that can be used for image processing.
Furthermore, the cost and scalability of ultrasonic scanners has been approaching the limitations of the piezoelectric transducer technology currently dominating the industry. Piezoelectric transducers are still made using “dice and fill” manufacturing processes in which individual piezoelectric elements are cut and then positioned individually on a substrate to form the transducer. Such processes are prone to the cost, non-uniformity, and non-scalability of machining and wiring.
The problem of transporting multiple channels of analog signals from a piezoelectric transducer array to the electronics in an ultrasound scanner has greatly limited the utility of the larger and denser arrays of transducers needed to push the resolution of ultrasound imaging forward and to enable high-quality 3D volumetric imaging.
Recent advances in the fabrication techniques of capacitive micromachined ultrasound transducers (CMUTs) allow high quality ultrasound transducers to be fabricated in the same semiconductor foundries that are currently driving the electronics industry. CMUT devices also have superior bandwidth and acoustic impedance matching capabilities when compared to piezoelectric transducers. Also, the increased flexibility available to design CMUT arrays enables advanced array design techniques that can suppress imaging artifacts, improve signal quality, and reduce channel counts. The ultrasonic imaging solutions using CMUT arrays that have heretofore been proposed, however, employ conventional architectures and signal processing paradigms, and thus suffer severe limitations and drawbacks.